Device for the combustion of solid fuels



July 14, 1959 R. GAUTHE 2,894,464

' DEVICE FOR THE COMBUSTION OF SOLID FUELS Filed Sept. 2'7, 1955 5 Sheets-Sheet 1 July 14, 1959 R. GAUTHE 2,894,464

DEVICE FOR THE COMBUSTION OF SOLID FUELS Filed Sept. 27, 1955 3 Sheets-Sheet 2 July 14, 1959 R. GAUTHE DEVICE FOR THE COMBUSTION 0F SOLID FUELS Filed Sept. 27, 1955 3 Sheets-Sheet 3 United States Patent DEVICE FOR THE COMBUSTION 0F SOLID FUELS Rene Gauth, Compiegne (Oise), France Application September 27, 1955, Serial No. 536,890

Claims priority, application France October 6, 1954 9 Claims. (Cl. 110-44) The present invention relates to devices for the combustion of coal and other fuels composed of relatively small pieces, for example between and 30 millimetres in size, and notably soft fuels, these devices being used in particular for the heating of low-power heat exchangers, such as a central heating boilers.

It is known that the use of the cheaper coals and principally the soft coals of small size has always been limited, in particular in household heating, owing to the difficulties encountered in obtaining a regular, complete and proper combustion.

The required simultaneous combustion of volatile substances and the regular progression of the combustion in the heart of the mass of coal, which is often agglutinated, is impossible to obtain in practice in heating installations in common supply at the present time for lean coals, anthracite or coke. Further, the burners used in industry for soft coals are unsuited for low-power devices on account for the space they consume. The object of the invention is to provide a device which is simple in constnuction, small, very easy to maintain and operate, which permits the combustion of coals of small size, and principally soft or bituminous coals, and which is of use in particular for the heating of low-power heat exchangers and notably central heating boilers.

The device embodying the invention comprises in combination with a furnace, which comprises a pre-combustion chamber having an inlet aperture for the fuel which is adapted to distil and coke at least partially the soft fuel and, adjoining this chamber, a zone provided with inlet apertures for the air of combustion for completing the burning of the fuel thus coked, a fuel feed device comprising a hopper containing a supply of fuel and a conveyer in communication with this hopper and, furthermore, with the inlet aperture of the precombustion chamher for progressively feeding the fuel from the hopper into said chamber and for automatically feeding the fuel, while it is being coked in this chamber, to the final combustion zone.

Owing to the initial distillation and coking of the soft fuel the combustion of the volatile substances is facilitated and this fuel is prevented from agglutinating in the final combustion zone, which is activated by air supply.

Experiments have shown that with this arrangement it is possible to obtain a perfect combustion of very soft fuels containing up to 38% of distillable products.

Further features and advantages of the invention will be apparent from the ensuing description, with reference to the accompanying drawings which are given solely by way of example and in which:

Fig. 1 is a vertical sectional view taken along line 1-1 of Fig. 2 of a device embodying the invention arranged at the base of a central heating boiler;

Fig. 2 is an elevational view of this device and of the lower part of the boiler;

Fig. 3 is a horizontal sectional viewof the boiler and 2,894,464 Patented July 14, 1959 ICC a horizontal sectional view of the device taken along line 33 of Fig. 1, and

Fig. 4 is a partial vertical sectional view on an enlarged scale of the upper part of the fuel conveyer.

In the illustrated embodiment the device is shown to be arranged at the base of a central heating boiler A.

This device comprises in combination, a furnace B and a feed device having a conveyer C and a hopper D containing a supply of solid fuel, for example small size soft coal, which the conveyer C progressively feeds from the hopper to the furnace B.

This furnace B, which in the illustrated example is combined with the base of the boiler A, comprises a precombustion chamber I which adjoins a final combustion zone II.

The precombustion chamber I comprises in combination: a solid vertical side wall 1 (Fig. 3) of the boiler (or an independent wall), an arch 2 of a refractory material forming an inlet aperture 3 which is inwardly divergent relative to the chamber, a solid lower portion of a vertical side "wall 4, which is parallel with the wall 1, and solid portions of a second wall 5. The wall 5 rests on supporting projections or lugs 5a provided on the side wall 1 and supports the arch 2 and the wall 4 under which it extends. The afore-mentioned expression refractory materia denoting the material of the arch 2 is intended to mean what is generally referred to as refractory material in the furnace art, that is, brick, masonry or the like, which in addition to its resistance to heat has heat-insulating properties.

The wall 4 is provided with slots 6 in the upper part thereof and forms a first grate.

The wall 5, which extends between the walls 1 and 4 and under the latter, comprises disposed between a and d (Fig. 1): a first lower horizontal solid portion ab which adjoins a second intermediate solid portion be which bends upwardly, the latter portion adjoining a third upper portion cd which is provided with slots 7 and forms a second grate.

The outlet or final combustion zone II is situated above the precombustion zone I and is bounded by the grate portions of the fixed walls 4 and 5, and a third grate 8 (Fig. 3). The latter extends substantially horizontally and laterally of the second grate and is level with the upper edge of the vertical 'wall 4, it being disposed on the opposite side of the latter to the chamber I. Thus the final combustion zone II extends upwardly of this grate 8 to one side of the precombustion chamber I.

This third grate 8 is, as known per se, pivotably mounted and keyed to a horizontal bar 9, so that it may be shaken from outside the furnace by means of a detachable lever engaged on a square end of the bar 9, this end being accessible through an opening provided in a plate 10 and normally closed by a pivotable shutter 11 (Fig. 2).

The conveyer C comprises a tunnel or passageway 12 having U-shaped cross-section. This passageway is rigidly held in position at its end adjacent the furnace, as by angle-irons l3 welded or bolted to the plate 10 which is attached by bolts 14 and nuts 15 to a frame 16 adapted to be attached to the boiler or other unit with which the device is combined. The passageway 12 is supported at its other end :by two support feet 17 which rest on the ground. The two side portions or flanges of this passageway extend beyond the plate 10 inside the furnace B, and the base of the passageway extends still further into the furnace at 18.

Movable inside the passageway 12 is a slide 19 freely slidable therein. This slide 19, which also has a U- shaped cross-section, comprises at its end adjacent the furnace a first thrust block or ram 20 fixed thereto, for

example by welding. A rigid flat strip 21 which prolongs and is rigid with the slide, carries at its end remote from the latter a second ram 22. Relative to the movement of the slide 19 toward the furnace, the rams 20 and 22 have a vertical leading face and an inclined trailing face so that each of them is wedge-shaped.

Disposed above each longitudinal side portion or flange of the slide 19 and fixed to the inner face of the flange of the passageway 12, as by welding or nuts and bolts, there is a strip 23 whose thickness is preferably slightly greater than that of the flange of the slide so that it completes the guiding of this slide in the passageway and furthermore forms a cover-plate between the side walls of the passageway and of the slide. A transverse fitted plate 24 fixed in the passageway 12, as by screws screwed into tapped holes formed in this plate, closes the end of the passageway 12 remote from the furnace, two notches 25 being formed in the plate 24 to clear the flanges of the slide 19 so that it may move freely in the passageway 12.

The hopper D is of sheet metal and comprises an upwardly divergent portion 26 and a lower portion 27 which forms an outlet aperture and is fitted into the passageway 12 above the strips 23 and against the plate 24. The hopper is secured to the passageway 12 for example by nuts the bolts (not shown). This hopper opens out into the passageway 12 through the aperture provided in its base, this aperture being situated substantially level with the upper edges of the strips 23, that is, above the flanges of the slide 19 and in consequence at a height above the base of the slide 19 which is greater than, or at least equal to the thickest layer of fuel intended to be conveyed by the conveyer C. For the purpose of regulating the thickness of the fuel fed by the slide, there is provided an adjustable regulator 28, the latter being applied against the lower part of the side of the hopper D which is adjacent the boiler. This regulator may be secured to the hopper for example by a bolt and a wingnut 30, the bolt extending through a vertical slot 31 formed in the regulator. The latter has a width which is slightly less than the inside width of the slide 19, so that it may move without friction between the two flanges thereof.

Between the hopper D and the plate 10, the upper part of the passageway 12 is closed by a cover 32 which is, for example, welded to the passageway and to the plate 10 or merely held in place by nuts and bolts. Formed in this cover 32, is an opening 33 (Figs. 1 and 4) which is closed by a shutter 35 mounted on the cover for pivotal movement about a pivot pin 36. An adjusting screw 37 permits adjusting the extent to which this shutter is opened.

Provided in the base of the passageway 12, there is an opening 38 (Fig. 1) which permits the extension therethrough of two lugs 39 welded under the slide 19. These two lugs form a fork through which extends a spindle 40 held in place by two pins 41. A link 42 is pivotably mounted at one end on this spindle and at the other end on a disc crank 43 which is connected by a calibrated safety pin 44 to the shaft 45 of a speed-reducing unit 46. The latter is fixed on a stand 47 on which the motor 48 connected to the unit 46 is mounted. The motor 48 may be connected to an electric main supply by the closure of a hand switch 49.

Another switch 50 connected in series with the switch 49 permits regulating the periods of operation of the speed-reducing unit 46 by means of any device 51 conventionally used in furnace-burner heating arrangements (thermostat placed at the end of the passageway 12 adjacent the furnace or a clock mechanism which closes the circuit for variable periods of time, and the like).

A conventional ash-pit 52 is provided below the furnace B (Fig. 1); this ash-pit has a door 53 (Figs. 1 and 2) which is pivotably mounted by a hinge 54 on a vertical spindle 55. Provided in this door there is an opening 56 having a shutter 57 which is pivotably mounted on a pivot pin 58 and is capable of being connected, in the conventional manner, by a chain 59 to the regulator of the boiler.

The device operates in the following manner:

The hopper D is filled with fuel, of pre-determined size, and the electric motor 58 is started up by closing the starting switch 49, the automatic switch 50 being normally closed. By means of the wing-nut 30 and the bolt 29 slidable in the vertical slot 31, the regulator 28 is so positioned that, for a given rate of feed of coal, the passageway 12 does not become completely filled. The reciprocatory movement of the slide 19 frictionally drives the coal particles toward the furnace past this regulator 28 against which the coal particles have a tendency to accumulate when the slide moves away from the furnace. The ram 26, owing to the gradual slope of its side facing the hopper, effects a shovelling operation on the coal accumulated aaginst the regulator for each return stroke to the right (as seen in Fig. l) of the slide and thus aids the advance of the coal toward the furnace B.

The transverse plate 24 opposes any escape of coal from the corresponding end of the passageway 12 and the strips 23 form, as has already been mentioned, joint covers above the flanges of the slide 1% and prevent fine particles of coal from entering between the passageway 12 and the slide.

The feed of the fuel to the furnace is effected by the rams. The fuel thus accumulates in the precombustion chamber I. A bright fire is then lit in this chamber with the aid of pieces of wood, for heating the refractories and the fuel. The air necessary for combustion is in part admitted through the opening 33 in the cover 32 of the passageway, this opening being controlled by the shutter 35, the position of which is adjusted by the screw 37. Air admitted is also controlled by the shutter 57 of the ash-pit 52.

When the temperature in the chamber I is suflicient, the volatile substances ignite. The progressive feed of fuel is continued until-the latter completely covers the upper grate portions of the fixed walls 4 and 5 and the movable grate 8.

Combustion thenceforth continues normally; at least a partial distillation and coking of the coal is obtained in the chamber I. The volatile substances burn in the zones I and II within the more or less coked mass which continues and completes its combustion on the grates.

Coal is cut ofl or supplied in accordance with the setting of the control device 51 which actuates the switch 58 of the supply circuit of the motor 43 in such manner that the coked fuel burning on the grates in the zone II of the furnace always fully covers them by forming a layer which is as thick as the size of the coke obtained is large.

The rate of operation of the boiler A is regulated by the conventional regulator of this boiler which controls the opening of the shutter 57 of the ash-pit through the chain 59, the operation of the boiler being thus set to suit requirements. The air may be admitted into the precombustion chamber I at a fixed rate by setting the screw 37 controlling the opening of the shutter 35 in accordance with the characteristics of the coal used, so that the refractory heat-insulating elements of the furnace B remain heated. Alternatively, the air admitted into the chamber I may be regulated in accordance with the rate of operation by connecting the shutter 35 to the chain 59.

The admission of secondary air is always possible through the shutter generally placed on the mouth of boilers.

The device of the invention exhibits numerous advantages:

It is of very simple construction, having a minimum of machined parts.

It may be adapted to small heat exchangers and particularly to the widely-used central heating boilers when using soft or bituminous coals of small size whose price is much less than that of lean coals of medium size in current use.

The method of feeding the coal under the hopper D and through the partially filled passageway 12, avoids the risk of jamming due to accidental introduction of foreign bodies in the hopper D or to the wedging of coal against the walls of the passageway 12, and permits the use of very crumbly coals.

The fractional combustion in relatively thin layers which are frequently agitated both in the coking chamber I and on the grates on the outlet side of the latter, permits a natural draught to be used.

The use of coals having a high content of volatile substances which readily ignite, avoids the risk of combustion ceasing, which often occurs when lean and similar coals are used, and permits easier regulation of combustion.

Although a specific embodiment of the invention has been described and shown, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Thus, the passageway 12 may be lengthened and the number of rams rigid with slide 19 increased, when it is not possible to dispose the hopper D near enough to the furnace B.

The electric motor 48 may be replaced by a hydraulic motor supplied by the water distributing pipes or a relief valve of the boiler in the case of a high pressure installation, this hydraulic motor exerting a direct action on the slide and being controlled by an electrically-operated valve which throttles or completely shuts off the liquid supply.

The horizontal pivotable grate may be replaced by an inclined grate which forms a supply of cinders and clinkers and comprises at its lower part a crusher actuated by the motor-speed-reducer unit or otherwise.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. Device for the combustion of in particular soft solid fuels in the form of small pieces, this device comprising a furnace including a lower precombustion chamber provided with a fuel inlet, for distilling and coking at least partially the soft fuel, and an upper final combustion chamber adjoining the precombustion chamber, said precombustion and final combustion chambers being separated by at least one grate for admitting air to the final combustion chamber and completing the 'burning of the coked fuel, a fuel feed device comprising hopper adapted to contain a supply of fuel, a tunnel which connects said hopper with said fuel inlet and is provided with an air inlet aperture, and a conveyor extending through said tunnel from said hopper into said precombustion chamber, and a refractory heat-insulating element disposed within said furnace adjacent to said fuel inlet, above said conveyor and at a level not higher than that of said grate, said refractory heat-insulating element defining the top of said precombustion chamber whereby sufficient heat and air are provided in said precombustion chamber for ensuring proper distillation and coking of said fuel.

2. Device as claimed in claim 1, further comprising refractory heat-insulating walls laterally defining said precombustion chamber on both sides of said refractory heatinsulatin-g element.

3. Device as claimed in claim 1, wherein an adjustable shutter is provided for said air inlet aperture in said tunnel to control the amount of air delivered to said precombustion chamber.

4. Device for the combustion of in particular soft, solid fuels in the form of small pieces, this device comprising in combination with a furnace which comprises a lower precombustion chamber which has a fuel inlet, for distilling and coking at least partially the soft fuel, and an upper final combustion chamber adjoining this precombustion chamber and provided with air inlets for admitting air for combustion and completing the burning of the coked fuel, a fuel feed device comprising a hopper adapted to contain a supply of fuel, a tunnel which connects said hopper with said fuel inlet, said tunnel comprising an air inlet aperture, and a conveyor extending through said tunnel from said hopper into said precombustion chamber for progressively feeding the fuel from the hopper into the precombustion chamber and progressively and automatically shifting the fuel as it is coked from the precombustion chamber toward the final combustion chamber, said furnace comprising a first vertical side wall having a height less than that of the furnace, and extending along one of the sides of the precombustion chamber, a substantially horizontal grate provided adjacent the upper edge of said first wall and forming part of the final combustion chamber, a refractory heat-insulating element in the form of an arch, the upper transverse portion of which is disposed adjacent the upper edge of the first wall on the other side thereof relative to said grate and at a lower level than that of said grate, said arch defining the top of said precombustion chamber by its upper transverse portion and the sides of said precombustion chamber by its upright portions and forming an inlet aperture which diverges inwardly relative to the [furnace and is adapted to be connected at its end which is outermost relative to the inside of the furnace to the end of the conveyor distant from the hopper so as to connect the conveyor to the precombustion chamber, and a second wall having a first lower horizontal so l-id portion which extends below said arch and support the lower edge of the first wall so as to form the bottom of the precombustion chamber and a second upwardly curved solid portion for forming the rear face of the precombustion chamber.

5. Device as claimed in claim 4, wherein said first wall is provided near its upper edge with a first series of air inlet apertures and the second wall comprises at the rear of the precombustion chamber a third upper portion provided with a second series of air inlet apertures, said two series of apertures, together with said grate being adapted to admit air to the final combustion chamber.

6. Device for the combustion of in particular soft solid fuels in the form of small pieces, this device comprising a furnace including a lower precombustion chamber provided with a fuel inlet, for distilling and coking at least partially the soft fuel, and an upper final combustion chamber adjoining the precombustion chamber, said precombustion and final combustion chambers being separated by at least one grate for admitting air to the final combustion chamber and completing the burning of the coked fuel, a fuel feed device comprising a hopper adapted to contain a supply of fuel, a tunnel which connects said hopper with said fuel inlet and is provided with an air inlet aperture, and a reciprocable slide extending through said tunnel from said hopper into said precombustion chamber for feeding the fuel thereinto and progressively and automatically shifting the fuel as it is coked from said precombustion chamber toward the final combustion chamber, and a refractory heat-insulating element disposed within said furnace adjacent to said fuel inlet above said slide and at a level not higher than that of said grate, said refractory heat-insulating element defining the top of said precomlbustion chamber, whereby suflicient heat and air are provided in said precombustion chamber for ensuring proper distillation and coking of said fuel.

7. Device for the combustion of in particular soft solid fuels in the form of small pieces, said device comprising a furnace the front part of which is provided with a fuel inlet, a fuel feed device comprising a hopper adapted to contain a supply of fuel, a tunnel which connects said hopper with said fuel inlet, said tunnel comprising an air inlet aperture, and a conveyor extending through said tunnel from said hopper into said furnace, the latter comprising a precombustion chamber and a final combustion chamber which are vertically and laterally spaced from one another, said precombustion chamber being defined by a lower transverse wall extending partially across the width of said furnace in front of said fuel inlet at the base of the latter, a side wall which has a height less than that of said furnace and extends upwardly from said lower transverse wall, and a refractory heat-insulating upper wall adjacent the upper edge of said side wall on one side of the latter and disposed above at least the part of said transverse wall which is adjacent said fuel inlet, the base of said final combustion chamber being defined by a grate disposed adjacent said upper edge of said side wall on the other side thereof relative to said upper *wall and at a level not lower than that of the latter, the fuel being fed by the conveyor from the hopper into said precombustion chamber, where it is distilled and coked, and being progressively shifted toward the final combustion chamber.

8. Device for the combustion of in particular soft solid fuels in the form of small pieces, said device comprising a furnace the front part of which is provided with a fuel inlet, a fuel feed device comprising a hopper adapted to contain a supply of fuel, a tunnel which connects said hopper with said fuel inlet, said tunnel comprising an air inlet aperture, and a conveyor extending through said tunnel from said hopper into said furnace, the latter comprising a precombustion chamber and a final combustion chamber which are vertically and laterally spaced from one another, said precombustion chamber being defined by a lower transverse wall extending partially across the width of said furnace in front of said fuel inlet at the base of the latter, a side Wall which has a height less than that of said furnace and extends upwardly from said lower transverse Wall, and a refractory heat-insulating element in the form of an arch, whose upper transverse portion is adjacent the upper edge of said side wall on one side of the latter and disposed above at least the part of said transverse wall which is adjacent said fuel inlet and Whose upright portions are disposed on both sides of said fuel inlet, the base of said final combustion chamber being defined by a :grate disposed adjacent said upper edge of said side wall on the other side thereof relative to said upper transverse portion of said arch and at a level not lower than that of the latter, the fuel being fed by the conveyor from the hopper into said precombustion chamber, where it is distilled and coked, and being progressively shifted toward the final combustion chamber.

9. Device as claimed in claim 8, wherein said side wall is provided near its above mentioned upper edge with a first series of air inlet apertures and said transverse wall comprises an upper portion at its end remote from said inlet aperture, said upper portion being provided with a second series of air inlet aperture/s, said two series of apertures together with said grate being adapted to admit air to said final combustion chamber.

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